Scaffold v1.0.0

Sources/EmbedderTool/StringLiteralEscaper.swift

@@ -0,0 +1,48 @@
+import Foundation
+
+enum StringLiteralEscaper {
+    static func rawTripleQuotedLiteral(from content: String) -> String {
+        let hashDelimiter = makeHashDelimiter(avoidingCollisionsIn: content)
+        return assembleLiteral(content: content, hashDelimiter: hashDelimiter)
+    }
+}
+
+private extension StringLiteralEscaper {
+    static let tripleQuote = "\"\"\""
+
+    static func assembleLiteral(content: String, hashDelimiter: String) -> String {
+        let opening = "\(hashDelimiter)\(tripleQuote)\n"
+        let closing = "\n\(tripleQuote)\(hashDelimiter)"
+        return opening + content + closing
+    }
+
+    static func makeHashDelimiter(avoidingCollisionsIn content: String) -> String {
+        let minimumHashCount = longestHashRunFollowingTripleQuote(in: content) + 1
+        return String(repeating: "#", count: minimumHashCount)
+    }
+
+    static func longestHashRunFollowingTripleQuote(in content: String) -> Int {
+        var longestRun = 0
+        var cursor = content.startIndex
+        while let tripleQuoteRange = content.range(of: tripleQuote, range: cursor..<content.endIndex) {
+            let hashRun = consecutiveHashCount(in: content, startingAt: tripleQuoteRange.upperBound)
+            longestRun = max(longestRun, hashRun)
+            cursor = advance(from: tripleQuoteRange.lowerBound, in: content)
+        }
+        return longestRun
+    }
+
+    static func consecutiveHashCount(in content: String, startingAt startIndex: String.Index) -> Int {
+        var count = 0
+        var index = startIndex
+        while index < content.endIndex, content[index] == "#" {
+            count += 1
+            index = content.index(after: index)
+        }
+        return count
+    }
+
+    static func advance(from index: String.Index, in content: String) -> String.Index {
+        content.index(after: index)
+    }
+}